1. Field of the Invention
The present invention relates to a ball spline linear motion rolling guide unit for rectilinearly moving an outer cylinder member along a ball spline shaft and, more particularly, to a small ball spline linear motion rolling guide unit whose outer cylinder can be put in the palm of the hand.
2. Description of the Prior Art
Most of such a kind of small ball spline linear motion rolling guide units have three or more ball tracks and have the performances of heavy load and high rigidity. However, since they are generally used under the conditions of light load and high rectilinear moving accuracy, the specifications of the linear motion rolling guide unit and the use conditions do not properly coincide.
On the other hand, since such a kind of ball spline linear motion rolling guide unit has a holding apparatus, the number of parts is large. The supporting apparatus comes into contact with the balls during the sliding motion or the like, so that the running performance is adversely influenced. Also, this unit is expensive.
Further, since this linear motion rolling guide unit is small and has many ball tracks, the movement of the balls from the track surface to the direction turning passage is suddenly performed. Thus, there are problems such that the motion of the balls becomes unnatural and the smooth operation of the linear motion rolling guide unit is obstructed.